The profiles of interleukin (IL)‐2, IL‐6, and interferon‐gamma production by peripheral blood mononuclear cells from house‐dust‐mite‐allergic patients: a role for IL‐6 in allergic disease

We have developed a model to measure cytokine production by peripheral blood mononuclear cells (PBMC) in vitro. In this report, we examine the production of interleukin-2 (IL-2), IL-6, and interferon-gamma (IFN-γ) by PBMC of house-dust-mite (Dermatophagoides pteronyssinus)-allergic subjects. When stimulated with specific allergen (D. pteronyssinus), PBMC of patients produced significant levels of IL-2 and high levels of IL-6, but little or no IFN-γ. Nonatopic control PBMC also produced IL-6, although at lower levels, but no IL-2 or IFN-γ. A ubiquitous antigen, streptokinase/streptodornase (SKSD), induced high levels of IL-2 in patients, but only low levels of IFN-γ and IL-6. Nonatopic controls produced similar levels of IL-2 and IL-6, but high levels of IFN-γ to SKSD. IL-2 and IFN-γ levels induced by the T-cell mitogen phytohaemagglutinin (PHA) were similar in patient and control groups, but IL-6 levels were significantly lower in the patients. IgE synthesis in vitro was shown only in atopic PBMC cultures stimulated with specific allergen. The major points can be summarized as 1) IL-2 production by atopic patients in response to allergen; 2) IL-6 production to allergen by both atopic and nonatopic patients, but significantly increased in atopic patients; and 3) defective IFN-γ production by atopic patients to both allergen and antigen. These findings suggest that IL-6 may be important in the immune response to inhalent allergens such as D. pteronyssinus, possibly by creating a cytokine environment favourable to a TH2 response, and that atopic patients exhibit a generalized defect of IFN-γ production, not related to the response to allergen.